You may remember the scene in A Fish called Wanda when Jamie Lee Curtis becomes totally wild when John Cleese starts speaking (fake) Italian.
It's an interesting thing to observe how some foreign languages carry with them their fare share of cultural prejudice, be they positive or not.
French and Italian for example are often perceived as being sexy to American ears which may not be the case with German or Spanish.
German sexyness? Hmmm... sounds unlikely doesn't it? Yet, German calls for other cultural values which certainly have certain sociological and historical grounds.
Languages as tools which raison d'être is to communicate are basically neutral in terms of associated values and cultural hints. Just like the many writing systems, Chinese ideograms, Egyptian hieroglyphs, Latin alphabet, Arabic or Nordic ones are neutral and don't carry with them any cultural underlying meanings. They're just written signs on stones, sand or paper like sounds are just... well sounds.
It's the peoples and their cultures which give the languages they speak such and such flavor which don't pertain to their languages in the first place.
It all has to do with the history and culture of the peoples whose languages we may find attractive, or not. History here is the key word which explains the nature of the perceptions attached to foreign languages. And to be more precise, the history our own culture shares with other ones.
One may object that the mere nature of some sounds makes them unpleasant to our ears but then again, it's a matter of cultural context and possibly personal tastes.
I don't feel particularly comfortable with Deutsch or Chinese sounds euphonically speaking but I nonetheless may associate these sounds to certain cultural standards.
At the end of the day, it all boils down to the clichés we associate foreigners with. French and Italian may sound sexy to certain American ears or romantic to Asians, they nonetheless carry with them other images which probably are not particularly sexy.
Now, who knows if a Japanese Jamie Lee Curtis doesn't wiggle on her bed when a Cambodian speaks (fake) Vietnamese to her?